Thermostats have been used for many years as a temperature sensitive switch which controls heating and/or cooling equipment for conditioning a space in which the thermostat, or a temperature sensor connected to the thermostat, is placed. In the well known manner, a simple thermostat can be adjusted to establish a temperature set point such that, when the temperature in the conditioned space reaches the set point, the thermostat interacts with the heating and/or/cooling equipment to take suitable action to heat or cool the conditioned space as may be appropriate for the season.
Modern thermostat systems, which take advantage of the ongoing rapid advances in electronic technology and circuit integration, have many features which provide more precise supervision of the heating and/or cooling equipment to achieve more economical and more comfortable management of the temperature of a conditioned space. Many modern thermostat systems include a real time clock, a memory and a data processor to run a process control program stored in the memory to accurately measure the temperature of a temperature sensor disposed in the conditioned space and to send control signals to the heating and/or cooling equipment to closely control the temperature of the conditioned space. Modern thermostat systems permit anticipating and minimizing hysterisis or overshoot of the temperature in the conditioned space. In addition, the program can specify different set points at different times of the day and week and may also include a “vacation” mode which employs different set points when the conditioned space is not occupied for an extended period.
Many modern thermostat systems have a central control device or unit that receives environmental sensor data from sensors remote from the central control device. These sensors can detect temperature, humidity, or other parameters that may be used in a control program by the central control device to control environmental control equipment. The environmental control equipment (comprising HVAC equipment, among others) responds to signals from the central control device to affect the ambient comfort in rooms of a conditioned space. Typically, a remote sensor signal is received by the central control device and its value compared with that of a pre-set setpoint. If the sensor value is sufficiently different from the setpoint, environmental control equipment is activated or de-activated in response thereto. Remote sensors can be connected by wire directly to the central control device or by wireless connection so that the control program can store the output of each sensor and associate it with an identifier for the remote sensor where the output originated.
Modern programmable thermostat systems also may act to control temperature in some rooms of out of all those in a conditioned space as a “zone”. Unfortunately, zone control requires dedicated equipment for the zone or duct dampers or deflectors to direct conditioned air to the zone rooms. This requires complexity and additional cost to the system. One form of zone control uses storage in a central control device storing all the signals from multiple remote environmental sensors in the zone. The control program calculates an average value from the stored values of the remote sensors and uses that average value as a control value. The control value is compared with a setpoint, whereafter environmental control equipment is activated or de-activated. The control value established by prior art thermostat systems can easily over- or under-condition a room where a user most desires environmental control.
There is a need for zone control in a thermostat system where remote sensor values are averaged for occupied rooms at a central control device. The averaged sensor data establish a zone control value. This zone control value more accurately reflects environmental conditions of rooms where the user most desires control of those environmental conditions.